The specific and important role of estrogens in promoting epiphyseal closure, even in males, has been recently characterized. However, the metabolic impact of estrogen's effect in the male has not been properly studied in humans. These studies were therefore designed to address the role of estrogen on both whole body protein metabolism and epiphyseal closure in males, through the use of an aromatase inihibitor (Anastrozole). Data generated from these studies may provide important information in the treatment of young males with growth hormone deficiency. These studies are conducted at the Nemours Children's Clinic in Jacksonville, Florida.